Hi there, @emmahuynh88 

You can check on the Banking page if QuickBooks can connect to your bank. 

1. Click Add account.
2. Search the name of the bank.
3. Enter your username and password to sign in, then select Continue.
4. Complete the security verification.
5. Select Add new to create a new account.
6. Then, select Connect.

If you're unable to find the bank, you can click the Request support for your bank option. I also added an article for you to learn more: How to identify the correct bank.

Here's an article about uploading your bank transactions that are beyond 90 days: Manually upload transactions into QuickBooks Online.

Thanks for dropping by.